Vehicle steady drifting control with safety boundary constraints

The study on active safety motion control of automobiles is not only of great significance to the protection of people’s lives and properties, but also of great significance to the development of unmanned driving technology under extreme conditions. Drifting maneuver suggests that the vehicle remains controllable when tires are at high slip conditions. Therefore, the research of drift control is helpful to achieve the active safety motion control of automobiles under extreme conditions. This paper focuses the steady drifting control with safety boundary constraints. The nonlinear 3-DOF vehicle model, the energy phase plane, the yaw acceleration isoclines, and sideslip rate isoclines are used to define the analytical expression of the safety boundary for steady drifting. The ILQR algorithm is innovatively applied to steady-state drift control with the state derivative cost, the state boundary cost and the control cost. The hardware-in-the-loop experimental results suggests ILQR controller can avoid high-frequency oscillations, compared to dynamic surface control. And the controller can better limit the yaw rate and sideslip angle within the constraint boundary by selecting appropriate state boundary weights, compared with the controller without state boundary constraints.